Devices to prevent spinal extension
This invention resides in an apparatus for inhibiting full extension between upper and lower vertebral bodies, thereby preventing pain and other complications associated with spinal movement. In the preferred embodiment, the invention provides a generally transverse member extending between the spinous processes and lamina of the upper and lower vertebral bodies, thereby inhibiting full extension. Various embodiments of the invention may limit spinal flexion, rotation and/or lateral bending while preventing spinal extension. In the preferred embodiment, the transverse member is fixed between two opposing points on the lower vertebral body using pedicle screws, and a cushioning sleeve is used as a protective cover. The transverse member may be a rod or cable, and the apparatus may be used with a partial or full artificial disc replacement. To control spinal flexion, rotation and/or lateral bending one or more links may be fastened to an adjacent vertebral body, also preferably using a pedicle screw. Preferably a pair of opposing links are used between the upper and lower vertebral bodies for such purposes.
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The present application is a continuation of commonly owned and co-pending U.S. patent application Ser. No. 10/444,883 filed May 23, 2003, the complete disclosure of which is hereby incorporated herein by reference in its entirety for all purposes. Additionally, the present application claims benefit under 35 U.S.C. § 119(e) from U.S. Provisional Application Ser. No. 60/383,041, filed on May 24, 2002, and U.S. Provisional Application Ser. No. 60/385,171, filed May 31, 2002, the entire contents of which are hereby expressly incorporated by reference into this disclosure as if set forth fully herein.
BACKGROUND OF THE INVENTIONI. Field of the Invention
This invention relates generally to spine surgery and, in particular, to apparatus for preventing spinal extension.
II. Description of the Related Art
Extension of the spine increases pressure on the facet joints, and this pressure may lead to low back pain in some patients, particularly those with arthritic facet joints.
A number of devices to prevent spinal extension have been described. One category of such devices allows spinal flexion but prevents spinal extension. Devices in this category can be divided into two broad subclasses. First, as described in U.S. Pat. No. 5,375,823, longitudinal shock absorbing devices can be connected to pedicle screws placed into adjacent levels of the spine. That is, paired longitudinal devices are placed into paired pedicle screws in the L3 and L4 vertebrae to prevent extension between L3 and L4.
Second, as described in U.S. Pat. Nos. 5.609,634 and 6,379,355, devices can be attached to the spinous processes between two vertebrae. For example, an elastomeric core may be strapped to the spinous processes of L3 and L4 to prevent spinal extension between L3 and L4.
SUMMARY OF THE INVENTIONThis invention resides in apparatus for inhibiting full extension between upper and lower vertebral bodies, thereby preventing pain and other complications associated with spinal movement. In the preferred embodiment, the invention provides a generally transverse member extending between the spinous process and lamina of the upper and lower vertebral bodies, thereby inhibiting full extension. Various embodiments of the invention may limit spinal flexion, rotation and/or lateral bending while preventing spinal extension.
In the preferred embodiment, the transverse member is fixed between two opposing points on the lower vertebral body using pedicle screws, and a cushioning sleeve is used as a protective cover. The transverse member may be a rod or cable, and the apparatus may be used with a partial or full artificial disc replacement (“ADR”). To control spinal flexion, rotation and/or lateral bending one or more links may be fastened to an adjacent vertebral body, also preferably using a pedicle screw. Preferably a pair of opposing links are used between the upper and lower vertebral bodies for such purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
This invention minimizes or eliminates spinal extension through the use of a generally transverse member, preferably anchored at two points on the same vertebra to prevent adjacent vertebrae from coming closer together. The preferred embodiment, shown in
The sleeve could be made of any compressible or resilient material that has cushion-like properties and sufficient tensile strength. For example, natural and synthetic rubbers, elastomers, encased gels and foams, and fiber-reinforced polymers may be acceptable.
The invention is not limited to use in conjunction with natural vertebral discs, and may be used with partial or full artificial disc replacements (ADRs). The motion preserving embodiments for posterior insertion that allow at least partial spinal flexion while inhibiting at least a certain degree of spinal extension may be particularly suited for use with an ADR. Patients may experience low back pain following ADR insertion. The pain may be related to arthritis of the facet joints. The device and method according to this invention attempt to preserve ADR motion while decreasing the forces across the facet joints, thereby mitigating such problems.
Claims
1. An apparatus for preventing full extension between upper and lower vertebral bodies, each having spinous processes and lamina, the apparatus comprising:
- a generally transverse member extending between the spinous processes and lamina of the upper and lower vertebral bodies, thereby inhibiting full extension.
2. The apparatus of claim 1, wherein the device is fixed at two opposing points on the lower vertebral body.
3. The apparatus of claim 2, wherein the device is fixed using pedicle screws.
4. The apparatus of claim 1, further including a cushioning sleeve covering the transverse member.
5. The apparatus of claim 1, wherein the transverse member is a rod or cable.
6. The apparatus of claim 1, further including a partial or full artificial disc replacement.
7. The apparatus of claim 1, further including a link to another vertebral body to inhibit spinal flexion, rotation, or lateral bending.
8. The apparatus of claim 7, wherein the link is fastened to the upper vertebral body using a pedicle screw.
9. The apparatus of claim 7, including a pair of opposing links extending between the upper and lower vertebral bodies.
10. An apparatus for preventing full extension between upper and lower vertebral bodies, comprising:
- a stretchable element connected between the upper and lower vertebral bodies in a compressed state, thereby allowing at least a limited degree of spinal flexion, lateral bending and axial rotation while inhibiting spinal extension.
11. The apparatus of claim 10, wherein the stretchable element is a spring.
12. The apparatus of claim 10, wherein the stretchable element is attached to the respective vertebral bodies using pedicle screws.
13. The apparatus of claim 10, further including a sleeve covering the stretchable element.
14. The apparatus of claim 13, further including a second stretchable element outside the sleeve.
15. The apparatus of claim 10, further including a partial or full artificial disc replacement.
16. The apparatus of claim 10, including a pair of opposing stretchable elements extending between the upper and lower vertebral bodies.
Type: Application
Filed: Sep 1, 2005
Publication Date: Dec 29, 2005
Applicant: NuVasive, Inc. (San Diego, CA)
Inventor: Bret Ferree (Cincinnati, OH)
Application Number: 11/217,549